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I'm working towards solar+battery mostly because I feel that my electric energy costs are unreasonably high and I scored a residential battery for free. Had I n

I'm working towards solar+battery mostly because I feel that my electric energy costs are unreasonably high and I scored a residential battery for free. Had I not gotten it for free, I would probably have bought one anyway just to give PG&E the finger.

PaulDavisThe1st 6y ago
Depending on the size of your array, the problem with battery storage is that to actually capture the full output of a moderately sized array would require an enormous battery bank. So large that almost nobody would have one large enough. You'll just be throwing away generated power. By contrast, being grid-tied gives the peak power output somewhere to go/something to do. Now, if you live somewhere where your year round electrical needs are roughly constant, this is less of an issue: just size the array (and the bank) appropriately for your needs, there won't be much excess power. However, here in New Mexico, my wife and I use very little electricity for 6 months a year, a bit more for 3 months and quite a lot for the remaining 3 months because we have heat pumps for heating during the (cold) winter. Consequently, there's a compromise involved in sizing the array, and in my case, I picked a size that ought to a little too small in the winter and a lot too big in the summer, with the goal of net-zero for the year overall. That means that in the summer, I've got oodles of excess electrical power. Batteries on site would be impractical to store it.
- zbrozek 6y ago
  I will almost certainly remain grid-tied for quite some years to come, so excess will go elsewhere. But I want to pull in fairly close to zero. Also, I'm in the Bay Area and my electricity needs will track sun pretty well. Heating is currently gas and cooling is electricity. I plan to end up with Mitsubishi ductless units sooner or later, at which point there will be more opportunity to balance out energy consumption. And I'm probably 1-2 years from owning an EV, given how our commuter car is holding together.

PaulDavisThe1st 6y ago

Depending on the size of your array, the problem with battery storage is that to actually capture the full output of a moderately sized array would require an enormous battery bank. So large that almost nobody would have one large enough. You'll just be throwing away generated power. By contrast, being grid-tied gives the peak power output somewhere to go/something to do. Now, if you live somewhere where your year round electrical needs are roughly constant, this is less of an issue: just size the array (and the bank) appropriately for your needs, there won't be much excess power. However, here in New Mexico, my wife and I use very little electricity for 6 months a year, a bit more for 3 months and quite a lot for the remaining 3 months because we have heat pumps for heating during the (cold) winter. Consequently, there's a compromise involved in sizing the array, and in my case, I picked a size that ought to a little too small in the winter and a lot too big in the summer, with the goal of net-zero for the year overall. That means that in the summer, I've got oodles of excess electrical power. Batteries on site would be impractical to store it.

zbrozek 6y ago
I will almost certainly remain grid-tied for quite some years to come, so excess will go elsewhere. But I want to pull in fairly close to zero. Also, I'm in the Bay Area and my electricity needs will track sun pretty well. Heating is currently gas and cooling is electricity. I plan to end up with Mitsubishi ductless units sooner or later, at which point there will be more opportunity to balance out energy consumption. And I'm probably 1-2 years from owning an EV, given how our commuter car is holding together.